EFB weighing 50 kg were pretreated with 2.9 M sodium hydroxide at 130 °C and 3.5 kg f/cm2 for 20 min. A solid-to-liquid ratio of 1:5 was applied. This optimal pretreatment condition was taken from a previous study [13]. Pretreated biomass was collected into a buffer tank through a cyclone and was washed using a belt presser.